PerspectiveAstronomy

Disclosing Identities in Diffuse Interstellar Bands

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Science  21 Jan 2011:
Vol. 331, Issue 6015, pp. 293-294
DOI: 10.1126/science.1200144

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Summary

Just as detectives use fingerprints to pin down criminals, astronomers use spectra to identify molecules in interstellar space. Astronomical spectroscopy, especially spectroscopy of molecular ions, is developing rapidly. Numerous interstellar negative ions, the very high abundance of H3+ in the Galactic center, and the extremely strong far-infrared absorptions of OH+, H2O+, H2Cl+, and CH+ have all been discovered during the last few years (1). In contrast to these rapid developments in the discovery of new molecular spectra, whose sharp features can be thought of as clean fingerprints, there exists a group of several hundred intriguing broad optical spectra (see the figure, panel A) called the diffuse interstellar bands (DIBs). These blurry fingerprints have defied attempts by many astronomers, physicists, and chemists to understand them for many decades. Maier et al. (2) now have a suspect in custody as the molecule responsible for DIBs—the linear carbene molecule, l-C3H2—but more evidence will be needed to get a conviction.